OCEANSIDE  In October 1944, as American planes bombarded Japan and closed in on victory in World War II, a Japanese mother wrote a five-page letter to her son, a lieutenant fighting on Iwo Jima, the site of some of the war’s fiercest fighting.

Machiko Hattori told her son, Gen-ichi, that the sweet potatoes were “growing as large as your daughter, Fumiko’s head.” The family prepares his dinner even though he isn’t there. “It feels that we are having dinner together with you.”

Above all, she tells her son that the family is praying for his victory, and she reassures him that the family is fine, despite that the war is “increasingly getting fierce” as they face “the final showdown” with the American forces.

Gentaro Hattori died on Iwo Jima, and for six decades, the letter remained forgotten while in the possession of a WWII Marine’s family.

On Friday, the missive will be reunited with the Hattori family, as the man who discovered the letter and Gen-ichi Hattori’s grandnephew will meet in Oceanside through the help of two sister-city organizations in Oceanside and Kisarazu, Japan.

“We wanted to thank the American who intended to return the letter to our family,” said Motoki Hattori, the grandnephew of the Japanese soldier. “Because we were feeling (sad) that a bone and a memento of Gen-ichi” was not with the family.

Hattori’s words underscore the importance of the letter to the surviving family. Families, in Buddhist tradition, collect the bones or remains of cremated loved ones, which are kept in an urn in the family’s household to honor, worship and pay tribute to the ancestors.

“The letter is precious. He touched the letter. It was on his person when he died,” said Samuel Yamashita, a history professor at Pomona University and author of “Leaves from an Autumn of Emergencies: Selections from the Wartime Diaries of Ordinary Japanese.” The book chronicles the lives of Japanese people during WWII.

“In the absence of bone fragments, this letter is all they have to remember him. This is an extension of him. You can understand the profound sorrow of not being able to find bodies of long ones, and why it would motivate a family to come halfway across the world to retrieve this letter.”

Letters and diaries were common during the World War II-era in Japan, and serve as some of the most poignant and vivid accounts of the war on record, Yamashita said. Many letters, however, were heavily vetted and censored to maintain Japanese morale.

What makes Machiko’s letter unique, Yamashita said, is its strong patriotism, which contrasts many letters and diaries during late 1944, when questions about the war and a sense of defeat began to pervade the country.

“The word ‘defeat’ appears in diaries beginning the summer of 1944,” Yamashita said. “One thing you can say about this letter is that the writer never questions that her son and the other soldiers were doing the right thing.

“But it is also upbeat and particularistic, ‘We’re cooking the dish you like, and the potatoes are growing,’” Yamashita said. “It has the kind of particularity that is meant to reassure and comfort the soldier, to say, ‘We are all fine.’”

Those involved with finding the soldier’s family called it a “miracle,” amplified by the tragedy of the earthquake and tsunami that struck Japan three weeks ago.

“Every time I think about what has happened, I get emotional,” said Vickie Prosser, an Oceanside council aide who serves as secretary of the Oceanside Sister Cities Foundation. “Given what has occurred over the past few weeks, the return of one bit of history to a very proud family is heart wrenching.”

The letter was bought a couple of years ago at a flea market in Charlotte, N.C., by Rex Butler, an antique collector from Cornelius, N.C. It was inside a box that contained other letters and memorabilia, including a map of Iwo Jima. Most of the letters were from John W. Puett, a Marine fighting on the island, written home to his son. It’s unclear how Puett, who survived the war, got Hattori’s letter.

Earlier this year, Butler became curious about its contents.

Butler said his passion for all things military and intrigue about the story of how the lives of an American and Japanese soldier intertwined on Iwo Jima motivated him to find both families.

“The respect the Japanese and Marines had for each other on that island was amazing,” said Butler, 58, who will also be in Oceanside for Friday’s ceremony.

Butler found the Marine’s family by posting the items on a collectors website. Puett’s son contacted him, and Butler returned the keepsakes, except for the Japanese letter.

“After that, I figured if I could find the Marine’s son, why couldn’t I find the family of the Japanese soldier,” Butler said.

After having a portion of the letter translated, he discovered that the soldier lived near Kisarazu, and through an Internet search, learned that Oceanside and Kisarazu were sister cities. He contacted Prosser, who got in touch with Shinji Kiriishi, a friend from Kisarazu and member of Oceanside’s sister-city counterpart. She was able to have the letter translated. By Feb. 22, Kiriishi had found the family in a town outside Osaka.

The grandnephew, Motoki Hattori, and his wife, Mihoko, arrived in Oceanside on Wednesday afternoon.

“Another miracle was necessary that our family was found,” Motoki Hattori wrote. “I want to thank all the people concerned with this letter.”